1. Field of the Invention
The present invention relates to an optical information processing apparatus for carrying out recording of data to and playback of data from an optical recording medium, and to an optical head used as a constituent component of the optical information processing apparatus.
When merely ‘optical recording medium’ is stated in this specification, this is deemed to include not only optical recording media but also magneto-optical recording media. When ‘optical information processing apparatus’ is stated in this specification, this thus includes magneto-optical disk apparatuses that carry out recording of data to and playback of data from a magneto-optical recording medium such as a magneto-optical disk. Moreover, when ‘optical head’ is stated in this specification, this is deemed to include magneto-optical heads.
2. Description of the Related Art
An example of a conventional optical head is shown in FIG. 5. In this optical head He, two objective lenses 91 and 92 are held in a lens holder 90, and a planar lens surface 92a of the objective lens 92 faces an optical disk D with an air layer 94 therebetween. Laser light that has traveled from a light source not shown in FIG. 5 is converged by the objective lenses 91 and 92, thus forming a beam spot on the optical disk D.
In such an optical head He, the lens surface 92a corresponds to the interface between the objective lens 92 and the air layer 94, which have different refractive indices to one another, and hence a phenomenon occurs in which some of the laser light that has traveled through the objective lens 92 is reflected by the lens surface 92a upon reaching the lens surface 92a. If the amount of the laser light reflected by the lens surface 92a is large, then the efficiency of irradiation of light onto the optical disk D will be poor, and hence it is desirable to reduce the amount of reflection. A light reflection preventing film 93 has thus conventionally been provided either over the whole of the lens surface 92a or else over the part of the lens surface 92a through which the laser light passes.
However, with this conventional means, there are problems such as the following.
The gap between the optical head He and the optical disk D is set to be very small, and hence the optical head He and the optical disk D may contact one another due to the optical disk D shaking while rotating or due to warping. In particular, if a floating slider method is adopted in which the optical head He is made to float up from the optical disk D when the optical disk D rotates, then the optical head He may contact the optical disk D when the optical disk D stops rotating. However, conventionally the light reflection preventing film 93 has merely been provided in an exposed state on the lens surface 92a facing the optical disk D. Conventionally, problems have been prone to occur, such as when the optical head He and the optical disk D contact one another, the light reflection preventing film 93 may contact the optical disk D directly and may be damaged, or even if the light reflection preventing film 93 does not contact the optical disk D directly, the light reflection preventing film 93 may peel off from the lens surface 92a due to the shock caused by the contact between the optical head He and the optical disk D.
In the case that the optical head is constituted as a magneto-optical head having a magnetic field generating coil (not shown in FIG. 5), it is necessary to prevent thermal damage to the coil during the manufacturing process of the magneto-optical head, and hence the formation of the light reflection preventing film 93 by vapor deposition or sputtering is carried out in a relatively low temperature atmosphere. However, this results in lower adhesiveness of the light reflection preventing film 93. As a result, the light reflection preventing film 93 becomes yet more prone to being damaged when the optical head He and the optical disk D contact one another.